DROP DATABASE deletes all user data and log files, as well as any backup and restore history for the database. If the log files are needed for a rollforward recovery after a restore operation, or the backup history required to restore the database, these files should be saved before issuing this command.
When you use the DROP DATABASE command, archived log files for the dropped database are not affected. You must manually move archived log files from the log archive path. If you do not move these log files, future database recovery operations that use the same archive log path might fail.
The database must not be in use; all users must be disconnected database before the database can be dropped.
To be dropped, a database must be cataloged in the system database directory. Only the specified database alias is removed from the system database directory. If other aliases with the same database name exist, their entries remain. If the database being dropped is the last entry in the local database directory, the local database directory is deleted automatically.
Below are the Step-by-Step process to drop DB2 Database
Step 1:
Login to the db2 instance. Example in my case db2inst1
Step 2:
$ db2 force application all
DB20000I The FORCE APPLICATION command completed successfully.
DB21024I This command is asynchronous and may not be effective immediately.
Step 3:
$ db2 stop
SQL1064N DB2STOP processing was successful.
SQL1064N DB2STOP processing was successful.